linux/drivers/gpio/gpiolib-acpi.c
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   1/*
   2 * ACPI helpers for GPIO API
   3 *
   4 * Copyright (C) 2012, Intel Corporation
   5 * Authors: Mathias Nyman <mathias.nyman@linux.intel.com>
   6 *          Mika Westerberg <mika.westerberg@linux.intel.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 */
  12
  13#include <linux/errno.h>
  14#include <linux/gpio.h>
  15#include <linux/export.h>
  16#include <linux/acpi_gpio.h>
  17#include <linux/acpi.h>
  18#include <linux/interrupt.h>
  19
  20struct acpi_gpio_evt_pin {
  21        struct list_head node;
  22        acpi_handle *evt_handle;
  23        unsigned int pin;
  24        unsigned int irq;
  25};
  26
  27static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
  28{
  29        if (!gc->dev)
  30                return false;
  31
  32        return ACPI_HANDLE(gc->dev) == data;
  33}
  34
  35/**
  36 * acpi_get_gpio() - Translate ACPI GPIO pin to GPIO number usable with GPIO API
  37 * @path:       ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
  38 * @pin:        ACPI GPIO pin number (0-based, controller-relative)
  39 *
  40 * Returns GPIO number to use with Linux generic GPIO API, or errno error value
  41 */
  42
  43int acpi_get_gpio(char *path, int pin)
  44{
  45        struct gpio_chip *chip;
  46        acpi_handle handle;
  47        acpi_status status;
  48
  49        status = acpi_get_handle(NULL, path, &handle);
  50        if (ACPI_FAILURE(status))
  51                return -ENODEV;
  52
  53        chip = gpiochip_find(handle, acpi_gpiochip_find);
  54        if (!chip)
  55                return -ENODEV;
  56
  57        if (!gpio_is_valid(chip->base + pin))
  58                return -EINVAL;
  59
  60        return chip->base + pin;
  61}
  62EXPORT_SYMBOL_GPL(acpi_get_gpio);
  63
  64static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
  65{
  66        acpi_handle handle = data;
  67
  68        acpi_evaluate_object(handle, NULL, NULL, NULL);
  69
  70        return IRQ_HANDLED;
  71}
  72
  73static irqreturn_t acpi_gpio_irq_handler_evt(int irq, void *data)
  74{
  75        struct acpi_gpio_evt_pin *evt_pin = data;
  76        struct acpi_object_list args;
  77        union acpi_object arg;
  78
  79        arg.type = ACPI_TYPE_INTEGER;
  80        arg.integer.value = evt_pin->pin;
  81        args.count = 1;
  82        args.pointer = &arg;
  83
  84        acpi_evaluate_object(evt_pin->evt_handle, NULL, &args, NULL);
  85
  86        return IRQ_HANDLED;
  87}
  88
  89static void acpi_gpio_evt_dh(acpi_handle handle, void *data)
  90{
  91        /* The address of this function is used as a key. */
  92}
  93
  94/**
  95 * acpi_gpiochip_request_interrupts() - Register isr for gpio chip ACPI events
  96 * @chip:      gpio chip
  97 *
  98 * ACPI5 platforms can use GPIO signaled ACPI events. These GPIO interrupts are
  99 * handled by ACPI event methods which need to be called from the GPIO
 100 * chip's interrupt handler. acpi_gpiochip_request_interrupts finds out which
 101 * gpio pins have acpi event methods and assigns interrupt handlers that calls
 102 * the acpi event methods for those pins.
 103 */
 104void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
 105{
 106        struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 107        struct acpi_resource *res;
 108        acpi_handle handle, evt_handle;
 109        struct list_head *evt_pins = NULL;
 110        acpi_status status;
 111        unsigned int pin;
 112        int irq, ret;
 113        char ev_name[5];
 114
 115        if (!chip->dev || !chip->to_irq)
 116                return;
 117
 118        handle = ACPI_HANDLE(chip->dev);
 119        if (!handle)
 120                return;
 121
 122        status = acpi_get_event_resources(handle, &buf);
 123        if (ACPI_FAILURE(status))
 124                return;
 125
 126        status = acpi_get_handle(handle, "_EVT", &evt_handle);
 127        if (ACPI_SUCCESS(status)) {
 128                evt_pins = kzalloc(sizeof(*evt_pins), GFP_KERNEL);
 129                if (evt_pins) {
 130                        INIT_LIST_HEAD(evt_pins);
 131                        status = acpi_attach_data(handle, acpi_gpio_evt_dh,
 132                                                  evt_pins);
 133                        if (ACPI_FAILURE(status)) {
 134                                kfree(evt_pins);
 135                                evt_pins = NULL;
 136                        }
 137                }
 138        }
 139
 140        /*
 141         * If a GPIO interrupt has an ACPI event handler method, or _EVT is
 142         * present, set up an interrupt handler that calls the ACPI event
 143         * handler.
 144         */
 145        for (res = buf.pointer;
 146             res && (res->type != ACPI_RESOURCE_TYPE_END_TAG);
 147             res = ACPI_NEXT_RESOURCE(res)) {
 148                irq_handler_t handler = NULL;
 149                void *data;
 150
 151                if (res->type != ACPI_RESOURCE_TYPE_GPIO ||
 152                    res->data.gpio.connection_type !=
 153                    ACPI_RESOURCE_GPIO_TYPE_INT)
 154                        continue;
 155
 156                pin = res->data.gpio.pin_table[0];
 157                if (pin > chip->ngpio)
 158                        continue;
 159
 160                irq = chip->to_irq(chip, pin);
 161                if (irq < 0)
 162                        continue;
 163
 164                if (pin <= 255) {
 165                        acpi_handle ev_handle;
 166
 167                        sprintf(ev_name, "_%c%02X",
 168                                res->data.gpio.triggering ? 'E' : 'L', pin);
 169                        status = acpi_get_handle(handle, ev_name, &ev_handle);
 170                        if (ACPI_SUCCESS(status)) {
 171                                handler = acpi_gpio_irq_handler;
 172                                data = ev_handle;
 173                        }
 174                }
 175                if (!handler && evt_pins) {
 176                        struct acpi_gpio_evt_pin *evt_pin;
 177
 178                        evt_pin = kzalloc(sizeof(*evt_pin), GFP_KERNEL);
 179                        if (!evt_pin)
 180                                continue;
 181
 182                        list_add_tail(&evt_pin->node, evt_pins);
 183                        evt_pin->evt_handle = evt_handle;
 184                        evt_pin->pin = pin;
 185                        evt_pin->irq = irq;
 186                        handler = acpi_gpio_irq_handler_evt;
 187                        data = evt_pin;
 188                }
 189                if (!handler)
 190                        continue;
 191
 192                /* Assume BIOS sets the triggering, so no flags */
 193                ret = devm_request_threaded_irq(chip->dev, irq, NULL, handler,
 194                                                0, "GPIO-signaled-ACPI-event",
 195                                                data);
 196                if (ret)
 197                        dev_err(chip->dev,
 198                                "Failed to request IRQ %d ACPI event handler\n",
 199                                irq);
 200        }
 201}
 202EXPORT_SYMBOL(acpi_gpiochip_request_interrupts);
 203
 204struct acpi_gpio_lookup {
 205        struct acpi_gpio_info info;
 206        int index;
 207        int gpio;
 208        int n;
 209};
 210
 211static int acpi_find_gpio(struct acpi_resource *ares, void *data)
 212{
 213        struct acpi_gpio_lookup *lookup = data;
 214
 215        if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
 216                return 1;
 217
 218        if (lookup->n++ == lookup->index && lookup->gpio < 0) {
 219                const struct acpi_resource_gpio *agpio = &ares->data.gpio;
 220
 221                lookup->gpio = acpi_get_gpio(agpio->resource_source.string_ptr,
 222                                             agpio->pin_table[0]);
 223                lookup->info.gpioint =
 224                        agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;
 225        }
 226
 227        return 1;
 228}
 229
 230/**
 231 * acpi_get_gpio_by_index() - get a GPIO number from device resources
 232 * @dev: pointer to a device to get GPIO from
 233 * @index: index of GpioIo/GpioInt resource (starting from %0)
 234 * @info: info pointer to fill in (optional)
 235 *
 236 * Function goes through ACPI resources for @dev and based on @index looks
 237 * up a GpioIo/GpioInt resource, translates it to the Linux GPIO number,
 238 * and returns it. @index matches GpioIo/GpioInt resources only so if there
 239 * are total %3 GPIO resources, the index goes from %0 to %2.
 240 *
 241 * If the GPIO cannot be translated or there is an error, negative errno is
 242 * returned.
 243 *
 244 * Note: if the GPIO resource has multiple entries in the pin list, this
 245 * function only returns the first.
 246 */
 247int acpi_get_gpio_by_index(struct device *dev, int index,
 248                           struct acpi_gpio_info *info)
 249{
 250        struct acpi_gpio_lookup lookup;
 251        struct list_head resource_list;
 252        struct acpi_device *adev;
 253        acpi_handle handle;
 254        int ret;
 255
 256        if (!dev)
 257                return -EINVAL;
 258
 259        handle = ACPI_HANDLE(dev);
 260        if (!handle || acpi_bus_get_device(handle, &adev))
 261                return -ENODEV;
 262
 263        memset(&lookup, 0, sizeof(lookup));
 264        lookup.index = index;
 265        lookup.gpio = -ENODEV;
 266
 267        INIT_LIST_HEAD(&resource_list);
 268        ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
 269                                     &lookup);
 270        if (ret < 0)
 271                return ret;
 272
 273        acpi_dev_free_resource_list(&resource_list);
 274
 275        if (lookup.gpio >= 0 && info)
 276                *info = lookup.info;
 277
 278        return lookup.gpio;
 279}
 280EXPORT_SYMBOL_GPL(acpi_get_gpio_by_index);
 281
 282/**
 283 * acpi_gpiochip_free_interrupts() - Free GPIO _EVT ACPI event interrupts.
 284 * @chip:      gpio chip
 285 *
 286 * Free interrupts associated with the _EVT method for the given GPIO chip.
 287 *
 288 * The remaining ACPI event interrupts associated with the chip are freed
 289 * automatically.
 290 */
 291void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
 292{
 293        acpi_handle handle;
 294        acpi_status status;
 295        struct list_head *evt_pins;
 296        struct acpi_gpio_evt_pin *evt_pin, *ep;
 297
 298        if (!chip->dev || !chip->to_irq)
 299                return;
 300
 301        handle = ACPI_HANDLE(chip->dev);
 302        if (!handle)
 303                return;
 304
 305        status = acpi_get_data(handle, acpi_gpio_evt_dh, (void **)&evt_pins);
 306        if (ACPI_FAILURE(status))
 307                return;
 308
 309        list_for_each_entry_safe_reverse(evt_pin, ep, evt_pins, node) {
 310                devm_free_irq(chip->dev, evt_pin->irq, evt_pin);
 311                list_del(&evt_pin->node);
 312                kfree(evt_pin);
 313        }
 314
 315        acpi_detach_data(handle, acpi_gpio_evt_dh);
 316        kfree(evt_pins);
 317}
 318EXPORT_SYMBOL(acpi_gpiochip_free_interrupts);
 319
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